Viscosity meter



Feb. 19, 1957 N. BREWER VISCOSITY' METER Filed July 22, 1952 BY fyi-w.

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/VrroRA/EX United States Patent (,)iiiice Patented Feb. 1 9, 1 957 VIsCosrrY METER Nathaniel Brewer, Newtown, Pa., assignor to Fischer &

Porter Company, Hatboro, Pa., a corporation of Penn- Sylvania Application July 22, 1952, Serial No. 300,164

8 Claims. (Cl. 73-56) The present invention relates to certain new and useful viscosity meters for continuously indicating viscosity of a fluid flowing through the meter.

The viscosity meter of the present invention includes a metering chamber of gradually. varying internal crosssection and a ilow and viscosity sensitive float therein forming therewith an orice varying in area with the position of the float in the tube, a xed orifice in series with said metering tube, which orifice is preferably (though not necessarily) insensitive to viscosity, and means for maintaining a constant differential pressure across said orifice and maintaining constant flow through the orifice and through the metering chamber, to eliminate the effect on the flow-rate through the metering chamber of iluctuations in the pressure at the inlet and/ or outlet side of the instrument.

One of the objects of the present invention is to provide a more eifective and more dependable viscosity meter which may be used for continuously indicating and/or recording the viscosity of fluid flowing through a line; the instrument of the present invention being preferably applied to a small sample stream of the liquid withdrawn from the main line and either returned to the main line further downstream or discharged to the open atmosphere into a collecting reservoir or discarding stream.

In one aspect or embodiment, the viscosity meter of the present invention includes two tapered chambers in parallel or shunt relation to each other, one a relatively long tapered metering chamber or tube having a relatively small angle of taper and containing a free-oatin-g viscosity-sensitive iioat, and the other a relatively short press-regulating tapered chamber or tube having a relatively steep angle of taper and containing `a relatively heavily Weighted lloat therein forming therewith a variable by-pass or spillway, and a viscosity-insensitive xed orifice in series with metering tube.

By this parallel or shunt relationship between the two tapered chambers or tubes and the series relationship between the metering tube and the Xed orifice, a single float within the metering chamber will directly indicate the viscosity of the uid passing through the metering chamber, by the position assumed by the tloat Within said chamber.

In the accompanying drawings wherein like reference characters indicate like parts:

Figure l represents a more or less diagrammatic vertical cross-sectional view of one embodiment of the viscositymeter of the present invention.

Figure 2 is a diagram showing one application of the viscosity-meter of the present invention.

Figure 3 is a diagram showing another application of the viscosity-meter of the present invention.

Figure 4 is a diagram showing still another application of the viscosity-meter of the present invention.

Figure 5a represents a side elevational view of a metering chamber and float therein of a dilerent form from that shown in Figure 1, and which may be used in lieu 2 of the tube 6 and loat 11 of Figure l (in the apparatus shown in Figure 1).

Figure 5b represents a vertical cross-sectional view of another metering chamber and float therein of a different form from that shown in Figure 1, and which may be used vin lieu of the tube 6 and lloat 1 1 of Figure 1 (in the apparatus shown in Figure 1).

The viscosity-meter of the present invention includes a generally upright metering tube 6 whose internal crosssectional area increases from the inlet end to the outlet end thereof, and which may be formed of glass or other transparent or translucent material where a direct-reading instrument is desired, or may be formed of an opaque material, such as metal, where a direct reading is not required but where, instead, auxiliary indicating means are associated with the float contained within the tube, to indicate, atsome remote point, the position of the lloat within the tube.

Whether of glass or metal, transparent, translucent or opaque, the metering tube may be either a plain tapered tube such as shown in U. S. Patents 2,321,041, 2,323,320 and 2,370,634, or it may be a tapered tube with three (or more) parallel bead-guides extending inwardly from the tapered inner bore thereof to guide the float, as shown in U. S. Patent 2,441,350, yor it may be a cylindrical tube with flutes extending outwardly from the cylindrical bore thereof, with the horizontal cross-section of the llutes gradually increasing from inlet to outlet end of the tube, as for instance, the uted tubes of U. S. Patents 2,333,884 (Figures 7-9), 2,350,343 (Figures 12-14), 2,384,800, 2,389,957, 2,403,849, 2,404,361 (Figures 6-16), 2,377,861, 2,388,672'(Figure l) and 2,417,352.

lf made of glass orrother non-metallic material and metallic conduits are required, then the metering tube 6 may be supported between suitable end-fittings 7 and 8 in which the metering tube is held in stuffing-glands 5, in fluidsealed relationship to the fittings. The end-ttings 7 and S carry stop members 9 and 10 which provide lower and upper limits of travel for the float 11 within the tube 6. The float 11 is a viscosity-sensitive iloat, namely, one which is so shaped that variations in viscosity in the fluid will cause it to change its position, vertically, in a stream of fluid having a constant rate of ow through the tube 6, that is, increases in viscosity will cause it to assume a position nearer the outlet end thereof and decreases in viscosity will cause it to assume a position nearer the inlet end thereof.

The inlet 12 of the lower litting 7 is connected to a constant-How outlet 13 of a housing designated generally by the numeral 14. The housing 14 includes a lower oat-weight housing 15, an upper housing portion 16 and an orice-retaining llange 17. The housing 16 is provided with an inlet 18 which is connected up-stream to a main line or is connected to the delivery line of a sampling pump, which, in turn, is connected so as to draw from the main line or from any other line, tank or reservoir the viscosity of the contents of which is to be measured and/ or recorded, or the Viscosity of the contents of which is to be used as the basis for controlling the flow of a reagent, diluent or the like tluid. The housing member 16 is also provided with an outlet 19 which is connected to the down-stream side of the same main line or may discharge to the open atmosphere, into any sample-collecting or discarding reservoir or stream. Within the housing portion 16 a short tapered tube 20 lis mounted, with a wide-angle tapered' borev 21. The tapered-bore member or sleeve 20, is preferably'm'ade separately and of a relatively hard and corrosion and abrasion resistant metal or the like, and is preferably detachably mounted in the housing portion 16 by being screw-threaded in place therein, or held in place byan outwardly expanding split annular retaining spring-ring (of steel or other spring metal or material) which is permitted to expand into the annular groove 34 of a depth less than the cross-section of the wire or body of the split-ring 33,'so that a portion of its cross-section will overlap or overlay the end of the sleeve 20, thereby toV keep it in place. Within' the short wide-angle tapered bore 21 a pressure-regulator fioat 22 is mounted for vertical motion; the lower edge of the tioat 22 defining an annular orifice of variable area in conjunction with the tapered bore 21, so that as the iioat 22 rises, the area of said orifice, between the float 22 and tapered bore 21, increases rapidly but generally linearly to the vertical movement of the float. A rod 23 extends downwardly from the iioat 22, through a free passageway 24 in the lower housing portion 15, and extends into the float-weight chamber 32, where it carries a fioat-weight 25 which is of a diameter substantially less than the interior diameter of the floatweight chamber 32,`and may be provided with an annular guide-ring or flange 26 which fits the interior diameter of the fioat-weight chamber 32 with just sufficient clearance to provide an adequate working clearance and fluidbypass clearance of such amount as will cause the ring or fiange 26 to give any desired dash-pot or dampening effect against any tendency of the float 22 to hunt when sudden changes in pressure are imposed upon it. The fluid fills the entire chamber 32 both above and below the guide-flange 26, so that the float-Weight 25 is at all times fully immersed in the fluid whose viscosity is being measured (although a special immersion liquid may also be used in certain cases in the chamber 32, different from that of the tiuid being measured).

The outlet 27 of the upper fitting 8 is connected to the orice-retaining flange 17, beneath which is an orifice plate or disc 28, having a thin-edged, viscosity-insensitive orifice 31 therein, whose diameter or area is less than the internal cross-sectional area of the conduit or passageway 30 and less than the maximum area provided between the float 11 of the interior of the metering tube 6 when the float is in its position nearest the large end of said tube 6.

The liquid entering the inlet 18 from the up-stream side of the line or from a reservoir or storage tank (with or without the aid of the circulating pump) passes through the passageway 24 into the inlet 12 of the lower or inlet fitting 7 (through the conduit 29) and ows through the metering tube 6 upwardly or in the direction of its increase in internal cross-sectional area, past the viscositysensitive fioat 11 and through the outlet 27 and the conduit 30 and through the orifice 31 in the orifice-plate or disc 28, which is held tightly between the flange 17 and the upper disc-seat of the housing member 16. The efliuent from the metering tube 6 then passes out through the down-stream outlet or discharge outlet 19 of the housing member 16.

ln addition to the ow path above indicated, a secondary or by-pass flow or spell-flow takes place past the float 22, according to the pressure of the liquid entering the inlet 18 and the back-pressure of the down-stream side of the system. The under-side of the float 22 is subjected to the up-stream pressure or inlet pressure of the liquid entering through the inlet 18, While the top-side of the float 22 is subjected to the down-stream pressure or discharge pressure of the liquid. Hence, the position assumed by the float 22 will be determined by the pressure-differential between the inlet pressure and the outlet pressure. The float-weight 25 shortens the vertical movement of the float 22 responsive to such pressuredifferential acting upon it, which pressure-differential acts upon it in an upward direction because the up-stream or inlet pressure is always greater than the down-stream or outlet pressure. As the fioat 22 rises however, the orifice formed between the fioat 22 andthe tapered-bore 21 increases so as to provide a greater by-pass for the liquid 4 as the pressure-differential between up-stream and downstream increases, thereby creating a constant differentialpressure across the orifice 31. This, in turn, results in a constant rate of ow through the metering tube 6, past the viscosity-sensitive float 11, notwithstanding wide fiuctuations of pressure of the liquid entering the inlet 18.

By reason of this constant rate of ow, the changes in vertical position of the viscosity-sensitive float 11 will indicate changes in viscosity; any particular position as` sumed by the float 11 representing a particular viscosity. By suitable calibrations applied to the tube or to a scale alongside of it, direct or relative reading of viscosity may be obtained at all times.

The viscosity-sensitive float 11 may also be used as the guiding element of a remote indicating instrument of any suitable character, such as that of U. S. Patents 2,481,196, 2,472,090, 2,380,399, 2,425,691 and 2,557,072, or of a recording instrument such as that of U. S. Patent 2,414,086 whereby the changes in viscosity will be indicated at some remote point or may be recorded on a paper disc or belt moving at a constant rate and suitably calibrated, to show viscosity of the flowing liquid throughout a given period of time and the float 11 of the present viscosity-meter may also be used to activate or sensitize a fiow-control mechanism such as that shown in U. S. Patent 2,481,496, whereby the fiow in a diluent feed-line or the like `may be regulated automatically to maintain any predetermined viscosity.

The orifice 31 in the orifice plate or disc 28 is what is generally called a fixed orifice. However, it may be a gate-valve type fixed orifice or other fixed orifice adjust able in size for purposes of changing the range er adjust vment of the instrument. Though the orifice may be of such an adjustable form or construction, it may yet be fairly considered as a fixed orifice, in the sense that it does not change its own effective size automatically by or as a result of the changes in the rate of' flow through or pressure-differential across the orifice. This is a contradistinctien of the variable-area type orifice formed by the float 11 and tube 6, whose effective size automatically changes as the position of the float changes. Hence, in referring to a fixed orifice it should be understood that such fixed orifices may either be a nen-adjustable xed orifice or an adjustable fixed orifice. .in either case, however, the orifice is preferably though not necessarily a viscosity-insensitive type, namely, presenting a thin edge to the liquid flowing through it; and preferably without any taper leading to the thin edge, on the 'up-stream of the orifice plate. It is not altogether necessary to have a viscosity-insensitive type orifice because the how-rate through the orifice is maintained constant and in a high Reynold number range, in which the effects of viscosity on the orifice are minimized.

A short guide-rod or extension 35 may bc aflixed to and extended upwardly from the fioat 22, and guided in the corresponding aperture in the hub portion of the spider 36 which may be held in place by a split-ring 37 in an internal groove, similar to the ring 33 and groove 34- hereinabove described. A bottom stop member 48, carried by a spider or spokes 4i, within a ring 42, may be provided at the bottom of the dont-weight chamber 32; held in place by the screwcap 43, to fix the bottommost position of the float 22.. This position is such that a zero or substantially zero by-pass is provided between the lower edge of the fioat 2.2 and the tapered inner bore 21 of the sleeve 20, when the weight 25 rests on the stop 40.

The fittings 7 and 8 may be held together by the outer metallic housing members or sections 38 and 39 of the construction shown in Patent 2,370,634. Thus, construction for holding'the fittings 7 and 8 in assembled relation to-each other and Vfor adjusting and tightening the stufling glands may be such as illustrated in Figures 1, 2, 3, 4 and A5', or as illustrated in Figures 6 and 7 of `Patent 2,370,634,

. v't'i to which reference may be had for the details in this iitting-and-housing construction to support the metering tube 6.

The sleeve 20 may have a plurality of holes 44 through its side-wall, above the tapered bore 21 thereof, for spilling out the by-pass iuid more directly into the area of the discharge port 19.

The viscosity-sensitive float in the metering tube 6 may be either of the shape shown in Figure 1 or of the shape shown in Figures a and 5b hereof; the latter being preferred. Earlier float-shapes 4substantially sensitive to viscosity changes are shown in Patent 2,321,041; the iioat 62 shown in Patent 2,426,263; the oat 14 shown in Patent 2,348,732; the iioat 24 shown in Patent 2,311,181, and the iioats 176 or 151 in Patent 2,426,393.

Thus, instead of the float 11 shown in Figure 1, I prefer to use a truncated conical oat 81 like that shown in Figures 5a and 5b with a relatively long continuous tapered surface and with the lower and upper edges rounded DE, to induce as close to a stream-line flow past the float as may be practicable and thus to produce a high response or sensitivity to viscosity. For a direct-reading viscosity meter according to the present invention using a bead-guide tube such as the tube 6 indicated in Figure l,- I may provide a guide-ring 82 beneath the lower small end of the float 81, of the same diameter as the maximum upper diameter of the iloat at 86; said ring 82 being held by three or four thin spokes 83 extending outwardly from a central apertured hub 84 which is riveted or otherwise fastened to the end of a downwardly extending rod 85 aiiixed to the lower end of the oat 81. By this means, the float 81, when disposed within the bead-guide tube 6 in Figure l, will be prevented from wobbling because it will be guided by the three vertical parallel beads of the tube 6, both at the large upper diameter of the ioat indicated by the arrow 86 as Well as by the correspondingly diametered guide-ring 82.

In using the float 81 in the bead-guide tube 6 in Figure v1, the vlower stop-member 9 would be shortened, to an extent such that when the lower riveted end of the rod 85 beneath the oat 81 comes to rest on top of the stopmember 9, the upper maximum-diameter 86 of the iloat 81 will be more or less at the Zero position of the taper of the tube 6, namely, at the position where the diameter of the tapered portion of the tube 6 will be but slightly greater than the diameter of the float at 86.

If a plain tapered tube (namely without any beadguides) is used, as for instance the plain tapered tube 87 shown fragmentarily in Figur-e 5a, -a dynamically stable viscosity-sensitive oat as for instance the float 62 shown in Patent 2,426,263 or the oat 24 shown in Patent 2,311,181 may be used, having substantial viscosity-sensitivity or viscosity-response.

Where a magnetic or an electro-magnetic pick-up is to be used for picking up and indicating the position of the iioat S1, a (solid or hollow) extension rod 88 is extended from one end of the float 81, co-axially therewith, into a non-magnetic metallic guide-tube 89 which is in liquid communication with the metering tube 87. The rod 88 carries a guide-ring or annular projection 90, which fits into the parallel-walled tube 89 with appropriate working clearance for guidance thereof, 'and above the guide-element 90 a further extension 91 carries one or two permanent magnets imbedded therein, which may act upon one or Va pair of permanent magnets movably mounted adjacent the tube 89 in the zone of the magnets within the member 91 so as to be carried thereby, thus transmitting the position of the oat 81 to an exterior mechanical or electrical system; or a permanent magnet or iron-core contained within `the non-ferrous extension 91 may be 'used to vary the inductance of an electrical circuit, one or several of whose coils surround the tube 89, thereby to indicate, at any suitable remote point, the position of the oat 81 or to operate a controller or recorder, in servo- -6 motor fashion, in the manner known in the art and shown in part by the patents above referred to.

A lower guide-rod 92 may be extended from the oat 81, in the direction opposite to that of the rod 88, and a corresponding guide-tube, similar to the guide-tube 89 is provided at the other end of the metering-tube 87 and in communication therewith, into which the guide-rod 92 may be extended, lfor guiding oat co-axially in relation to the headless tapered tube S7; all in the manner known in the art and shown in part by the patents and publications above cited.

In Figures 2, 3 and 4 I have shown several applications of the viscosity-meter of the present invention. Figure 2 shows the application of the viscosity-meter to a storage tank; the liquid whose viscosity is to be measured being admitted into the meter by the valve shown, and the circulating pump serving to move the liquid through the meter and storage tank.

In the application shown in Figure 3 the liquid is withdrawn from and returned to the main line, with the aid of the circulating pump.

In the application shown in Figure 4 an automatic recording and controller instrument 100, such as that show-n, for example, in Catalog No. 50 published by the 'Fischer & Porter Company (of Hatboro, Pa.) entitled Exhibiting and Controlling Instruments for Use With Flowrator Meters is applied t-o the instrument of Figure l, in the manner indicated in Figure 4; the float 1,1 being provided with an upper extension which enters the pick-up porti-on of such automatic recording controller.

For the magnetic pick-up of the iioat position see the illustration 5 on page 5003 of the aforesaid catalog. For the electrical transmission for remote indicating viscosity, see illustrations 9 and 13 on pages 5006 and 5007, respectively, of the aforesaid catalog. For the controller see illustrations 3l and 39 on pages 5015 and 5019, respectively, of the aforesaid catalog. For the recording instrument see the cover page of the aforesaid catalog.

In the application s-hown in Figure 4 the controller may be connected through the connection 10-1 with a diaphragm air-motor valve 102, which may be of lthe kind and construction shown in Catalog 70-B published by the Fischer & Porter Company (-o-f Hatboro, Pa.) entitled Valvrator Diaphragm Air Motor Valve (see ilustra- -tions B and C on page 7003 of said catalog). By this means the ilow of any reagent diluent or other fluid may me regulated by Ithe fluid being measured. Thus, for instance, as the viscosity in the main line increases, the amount yof diluent added may be correspondingly increased and thus the viscosity of the discharge from the main line kept constant. Any other Huid additive may be controlled by the viscosity of the liquid being measured.

The valve-actuator means for the application shown in Figure 4, may also be of `the type shown in Patent 2,472,090.

Indicator means such as shown in Patent 2,425,691 may also be used with iloat 11.

Having described my invent-ion what I claim as new and desire to protect by Letters Patent ig the following:

l. A viscosity meter including an upright metering tube whose horizontal internal cross-sectional area increases 4from a threshold point near the inlet end thereof yto .a limiting point near the outlet end thereof, a viscosity-sensitive metering float in said metering tube forming therewith a passage of variable effective area for the passage of uid past said metering float, the area of said pas-sage increasing as the oat ass-urnes a position nearer the out-- let end thereof and decreasing as the lioat assumes a position nearer ythe inlet end thereof, a differential pressure regulator shunted across the inlet and outlet of said meterling tube, and means forming a flow-restricting oriiice between said metering tube and said regulator and disposed in series with said 4metering tube, the relation-ship between suc-h orifice-means and said metering tube and said metering float being such that the pressure-drop across said orifice-means is substantially greater than the pressure-drop across said metering-float, said regulator providing a relatively constant pressure-drop across said orifice-means and across said metering tube and providing a relatively constant rate-.of-flow through said metering tube.

2. A viscosity meter including an upright tapered metering tube having its smaller end down and its larger end up, a viscosity-sensitive float operatively disposed within said tube forming therewith a passage of variable effective area for the passage of fluid past said float, ,an upstream inlet connected to the lower small end of said metering tube and a down-stream outlet connected to the larger upper end `of said metering tube, a constant differential pressure regulator shunted across said up-stream inlet and said down-stream youtlet and arranged to form a liquid passageway between said inlet and said outlet bypassing said metering tube, and means forming a flowconstricting orifice between said metering tube and said regulator and in series with said metering tube, said constant differential pressure regulator having its' inlet side subjected to the 11p-stream pressure and its outlet side subjected to the down-stream pressure, the relationship between said orifice-means and said metering tube and the oat therein being such that the pressure-drop across said orifice-means is substantially greater than the pressuredrop across said oat, said constant differential-pressure regulator providing a relatively constant pressure-drop across said orifice-means and across 'said metering tube and providing a relatively constant rate-of-liow through said metering tube.

3. A viscosity meter including an upright tapered 4metering .tube with its smaller end down and its larger end up, a viscosity-sensitive float in said tube, said tube connected in series with an 11p-stream inlet connected to the small end of the tapered tube, and with a down-stream outlet connected -to the large end of the tapered tube, a differential pressure regulator, having a by-pass passageway for liquids, shunted across said up-stream inlet `and the down-stream outlet of said metering tube and means forming a flow-constricting orifice between said metering tube and said by-pass passageway and in series with said metering tube, the relationship between said orifice-means and said metering tube and the oat therein being such that the pressure-drop across said orifice-means is substantially greater than the pressure-drop across said float, said differential-pressure regulator providing a relatively constant pressure-drop across the said orice-means and across said metering tube and providing a relatively constant rate-of-iow through said metering tube.

4. A viscosity meter including an upright metering.A

tube, a viscosity-sensitive metering float therein, said metering tube and said metering fioat together forming a passageway of variable effective cross-sectional area for the passage of uid through said metering tube past said metering float, the effective cross-sectional area of such passageway varying with the position assumed by said float within said metering tube along the length of said tube, and said effective cross-sectional area increasing as the oat assumes a position nearer the outlet end of said tube and decreasing as the float assumes a position nearer the inlet end of said tube, a differential pressure regulator, having a by-pass passageway of variable effective cross-sectional area shunted across thte inlet andV outlet of said metering tube exteriorly thereof, said variable by-pass passageway being formed of a stationary regulator opening and a movable regulator float disposed in operative juxtaposition thereto and so related to each other that as the movable regulator float moves in relation to said stationary regulator opening, the effective cross-sectional area of the by-pass passageway formed therebetween varies in effective cross-sectional area and increases as said movable regulator float moves in the direction of the outlet side of said regulator opening and decreases` as said movable regulator oat moves in the direction of the inlet side of said regulator opening, a weight connected with said movable regulator float, and means forming a ow-constricting orifice between said metering tube and said regulator and in series with said metering tube, the relationship between such orificemcans and said metering tube and the metering float therein being such that the pressure-drop across said orifice-means is substantially greater than the pressuredrop across said metering oat in the metering tube, said differential-pressure regulator providing a relatively constant pressure-drop across said orifice-means and across said metering tube and providing a relatively constant rate-of-flow through said metering tube.

5. A viscosity` meter including an upright metering tube whose horizontal internal cross-sectional area increases from a threshold point near the inlet end thereof to a limiting point near the outlet end thereof, a viscosity-sensitive metering float in said metering tube forming therewith a passage of variable effective area for the passage of fluid past said metering float, the area of said passage increasing as the metering float assumes a position nearer the outlet end thereof and decreasing as the metering float assumes a position nearer the inlet end thereof, mechanical means for guiding said metering tioat axially of said metering tube with minimum contact therewith, a differential-pressure regulator shunted across the inlet and outlet of said metering tube, with the inlet side of said regulator connected with the inlet of said tube and with the outlet side of said regulator connected with the outlet of said tube, and means forming a flow-constricting orifice between said metering tube and said regulator and in series with said metering tube, the relationship between such orifice-means and said metering tube and the float therein being such that the pressure-drop across said orifice-means is substantially greater than the pressure-drop across the metering oat, said differential-pressure regulator providing a relatively constant pressure-drop across said orifice-means and across said metering tube and providing a relatively constant rate-of-flow through said metering tube.

6. A viscosity meter including an upright metering tube whose horizontal internal cross-sectional area increasesV from a threshold point near the inlet end thereof to a limiting point near the outlet end thereof, a viscosity-sensitive metering float in said metering tube forming therewith a passage of variable effective area for the passage of fluid past said metering float, the area of said passage increasing as the metering float assumes a position nearer the outlet end thereof and decreasing as the metering float assumes a position nearer the inlet end thereof, mechanical means for guiding said metering float axially of said metering tube with minimum contact therewith, a differential-pressure regulator having an inlet andl an outlet, shunted across said metering tube, said regulator including a relatively short tapered regulator tube with a relatively steep taper intermediate said inlet and said outlet, with its small end down and towards said inlet and its large end up and towards said outlet, and with its axis substantially vertical, a regulator float within said tapered regulator tube forming a by-pass passageway with said tapered regulator tube whose eective area varies according to the position of the regulator float, a weight-receiving chamber, and a relatively heavy weighty connected with said regulator float and disposed within said chamber, said chamber being in communication with the interior of said regulator, and means forming a fiow-constricting orifice between said metering tube and said regulator and in series with said metering tube, the relationship between such orifice-means and said metering tube and its metering float being such that the pressure-drop across said orifice-means is substantially greater than the pressure-drop across the metering float, said differential-pressure regulator providing a relatively constant pressure-drop across said orificemeans and across said metering tube and providing a relatively constant rate-of-ilow through said metering tube.

7. A viscosity meter including an upright metering tube whose horizontal internal cross-sectional area increases from a threshold point near the inlet end thereof to a limiting point nea-r the outlet end thereof, a viscositysensitive metering iioat in said metering tube forming therewith a passage of variable effective area for 'the passage of fluid past said metering oat, the area of said passage increasing as the metering float assumes a position nearer the outlet end thereof and decreasing as the metering float assumes a position nearer the inlet end thereof, mechanical means for guiding said metering float 'axially of said metering tu'be with minimum Contact therewith, a differential-pressure regulator having an inlet and an outlet, shunted across said metering tube, said regulator including a relatively short tapered regulator tube with a relatively steep taper intermediate said inlet and said outlet, with its small end down and towards said inlet and its large end up and toward said outlet, and with its axis substantially vertical, a regulator iloat within said tapered regulator tube forming a passage with said tapered regulator tube whose eifective area varies according to the position of the regulator float, a weight-receiving chamber, and a relatively heavy weight connected with said regulator yfloat and disposed within said chamber, said chamber being in communication with the interior of said regulator but outside .of the path of the stream flowing through said regulator, and means forming a flow-constricting orifice between said metering tube and said regulator and in series with said metering tube, the relationship between such orifice-means and said metering tube and its metering float being such that the pressure-drop across said orifice-means is substantially greater than the pressure-drop across saidmetering oat, said differentialpressure regulator providing a relatively constant pressuredrop across said orifice-means and across said metering tube and providing a relatively constant rate-of-ow through said metering ltube.

8. A viscosity meter including an upright metering tube whose horizontal internal cross-sectional area increases from a threshold point near the inlet end thereof to a limiting point near the outlet end thereof, a viscosity-sensitive metering oat in Vsaid metering tube forming :therewith a passage of variable effective area for the passage of uid past said metering oat, the area of said passage increasing as the metering float assumes a position nearer the outlet end thereof and decreasing as the metering float assumes a position nearer the inlet end thereof, mechanical means for guiding said metering iloat axially of said metering tube with minimum contact therewith, a differential-pressure regulator shunted across the inlet and outlet of .said metering tube, said regulator having an inlet and an outlet, a relatively short tapered regulator tube with a relatively steep taper intermediate said inlet and said outlet, with its small end `down towards the inlet and vwith its large end up and towards the outlet and with its axis substantially vertical, a regulator float within said tapered regulator tube forming a passage with said tapered regulator tube whose effec-tive area varies according to the position of the regulator float, float-guiding means for said regulator iioat having a relatively small guiding-contact surface, a loading chamber in communication with the interior of said regulator, means within said chamber for heavily loading the regulator float in the direction of minimum passage between :it and the tapered regulator tube, said iloat-loading means, lsaid regulator float and said float-guiding means therefor being arranged to suspend the regulator iloat in the moving stream of iluid under operating conditions, with minimum guiding friction, with the inlet side of said regulator connected with the inlet of ysaid metering tube and with the outlet side of said regulator connected with the outlet of said metering tube, and means forming a flow-constricting orifice 'between said metering tube and said regulator and in series with said metering tube, the relationship between such orificemeans and ysaid metering tube and metering float being vsuch that the pressure-drop across said orifice-means is substantially greater than the pressure-drop across the metering float, said `diiferential-pressure regulator providing a relatively constant pressure-drop acrosssaid orificemeans and across said metering tube and providing arelatively constant rate-of-flow through said metering tube.

References Cited in the le 'of this patent UNITED STATES PATENTS FranceV Oct. 2, 1939 

